Advances in technology have resulted in an increasing demand for system-on-chip products where both analog and digital signal processing are desirable. For example analog circuits capture an analog signal from the surrounding environment and transform the signal into bits which are then transformed into signals for driving digital circuitry and output functions. Increasingly it is advantageous to have both the analog circuitry and digital circuitry in close proximity, for example in the form digital blocks and analog blocks of circuitry which function together to implement the function of the system, also referred to as mixed mode systems.
One immediate problem with the integration of analog and digital circuitry blocks is the increase in power consumption. The design constraints that inform the design of digital blocks include the need for fast signal transmission and low power consumption. On the other hand in analog circuitry, as device sizes have decreased, the power supply to the circuitry has been decreased, leading to susceptibility of a signal to noise levels in the circuitry. As a result, a differential signal is frequently used including a local Vdd boost to decrease sensitivity to thermal noise.
In metal-insulator-metal (MIM) structures, which are included in analog circuitry building blocks, low and reliably produced stable capacitances are of primary importance, for example in digital/analog converters, since low capacitance values require less power.
Many analog and mixed mode systems rely on precise reproducibility in the electronic properties of circuit component structures, such as MIM structures, to achieve the electrical matching of the various circuitry components. Electronic mismatch of circuitry components results in reduced signal processing quality and is adversely affected by deviations in processing conditions or the physical stability of component structures in processing and operating environments, for example a capacitance value of an MIM structure.
The capacitance of an MIM capacitor structure may be affected by several variables including the thickness of the capacitive dielectric layer which may be adversely affected by processing and operating conditions.
There is therefore a continuing need in the semiconductor device processing art for improved MIM capacitor structures and manufacturing processes to achieve reproducibly reliable and consistent electrical properties including capacitance.
It is therefore an object of the invention to provide improved MIM capacitor structures and manufacturing processes to achieve reproducibly reliable and consistent electrical properties including capacitance, while overcoming other deficiencies and shortcomings of the prior art.